Cannot send patch.

[Fis Trivial]

It seems that I can't send anything to the patch mailing list in recent
days. The last patch I sent is:

http://lists.gnu.org/archive/html/guix-patches/2018-04/msg00116.html

After that, I couldn't send mail to the list. I use mu4e and with
outlook, both told me that I did send out the mail, but the list doesn't
display my mail and I didn't get any acknowledgement.

I subscribed to the list and can recieve mails from it.